The TLS (pre-1.3) ChangeCipherState message is usually used to indicate
the switch from the unencrypted to encrypted part of the handshake.
However, it can also be used in cases where there is an existing
session (such as during resumption handshakes) or when changing from
one cipher to a different one (such as during renegotiation when the
cipher list offered by the client has changed).  This test serves
to exercise such situations, allowing us to detect whether session
objects are being modified in cases when they must remain immutable
for thread-safety purposes.
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/10943)

(cherry picked from commit 3cd14e5e65011660ad8e3603cf871c8366b565fd)